<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
	.a1{
		background-color:#FC9;
		width:700px;
		height:100px;
		float:left;
		margin-bottom:20px}
	.a2{
		background-color:#9F3;
		width:190px;
		height:600px;
		float:left;
		margin-right:10px}
	.a3{
		background-color:#C66;
		width:500px;
		height:600px;
		float:left}
	.big{
		width:700px;
		margin:auto}
</style>
</head>

<body style="background-color:pink;">
<div>
	<div class="big">
    	<div class="a1"></div>
        <div class="a2"></div>
        <div class="a3"></div>
    </div>
</div>
</body>
</html>
